Removable airwash cartridge or cassette for grit drying system

ABSTRACT

An abrasive blasting system including a magnetic drum, an airflow generator configured to create airflow, and a removable airwash cartridge that includes one or more angular feedplates with lips extending therefrom.

RELATED APPLICATIONS

This Application claims priority to co-pending U.S. Provisional Patent Application Ser. No. 61/409,400 filed Nov. 2, 2010; the contents of which are incorporated herein in their entirety.

BACKGROUND

Abrasive blasting systems are used in preparing surfaces for painting. Some abrasive blasting systems recycle blast media being used. The blast media may be garnet, specular hematite, steel grit, steel shot, and other medias. The blast media is often cleaned at a certain stage in the recycling process to remove dust from the media, as the blast media is generally ineffective below a certain size (e.g., 15 mesh for steel grit), as understood in the art. Cleaning the blast media typically includes passing air across the blast media, so that as the blast media is collected in a hopper, the dust is already removed from the blast media, thereby making the blast media ready for use in blasting against a surface.

SUMMARY

The principles of the present invention provide for dropping blast media off an edge or lip and allowing the blast media to fall vertically while air under suction or pressure is pulled or pushed past the effective “waterfall” of blast media. As the blast media falls vertically, this stream of air is pulled or pushed perpendicular to the dropping grit, under the lip from which the blast media is falling, thus allowing the airflow to remove particles that have a lower density than the blast media that is intended to be retained. Thus, the heavier blast media drops while the lighter particles are moved sideways and pulled and/or pushed out of the stream of blast media that is intended to be kept for recycling and reuse.

In one embodiment, a removable airwash cartridge may be utilized to provide for the blast media to be cleaned. The removable airwash cartridge may include multiple stages so that multiple “waterfalls” of blast media are created. By having multiple “waterfalls,” additional dust and debris may be cleaned from the blast media. By using a removable airwash cartridge, a user is provided with the ability to change an airwash from one design to another in a simple manner (i.e., take one out and put another in). The different designs of airwashes may be used in different circumstances, such as for supporting different blast media, providing different levels of cleaning, and so forth. One embodiment may provide for a clear retaining wall (i.e., the wall that is positioned along the outside of the abrasive blasting system, thereby allowing for someone to see how the blast media is flowing and being cleaned.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of an illustrative separator module and blast media airwash module of an abrasive blasting system;

FIG. 2 is an illustration of a zoomed-in view of the blast media airwash module of the abrasive blasting system of FIG. 1;

FIG. 3 is an illustration of an illustrative removable airwash cartridge of an abrasive blasting system; and

FIG. 4 is an illustration of the removable airwash cartridge of the abrasive blasting system of FIG. 3.

DETAILED DESCRIPTION OF THE DRAWINGS

Airwashing blast media of a recycling abrasive blasting system may involve dropping the blast media or media off an edge or lip and allowing it to fall vertically while air under suction or pressure is being pulled or pushed past the effective “waterfall” of blast media or grit. As the blast media falls vertically due to gravitational forces, the stream of air or airflow is pulled or pushed substantially perpendicular with respect to the direction of the dropping grit, under the lip from which it is falling, allowing the airflow to remove particles that have a lower density than the grit that is intended to be retained. Blast media tends to be effective in preparing a surface if it is 15 mesh or larger, as understood in the art. Depending on the surface being prepared, blast material, and other factors, however, other size blast media may be collected by adjusting airflow, angle of feedplate, length of lips, and other variables. Thus, the heavier blast media drops while the lighter particles are moved sideways and pulled and/or pushed out of the stream of blast media that is intended to be kept for recycling and reuse. The lighter material, mostly dust, but also small, broken-down blast media, is then typically disposed of. Although the blast media flow and process described herein uses gravitational forces to provide for the airwash environment, it should be understood that alternative configurations of airwash environments that incorporate the principles of the present invention may alternatively be utilized.

The airwash process depends on the separation of lighter materials while the heavier grit to be recycled and reused falls vertically. Thus, the airwash process may often be used as the final stage of cleaning in a multi-step process that may or may not include: (i) mechanical separation using screening, (ii) magnetic separation using a rotating magnetic drum, or (iii) other forms of separation.

FIG. 1 is an illustration of an illustrative separator module and blast media airwash module of an abrasive blasting system. As shown, blast media is attracted and maintained by a rotating magnetic drum if the blast media is metallic, of course. Non-metallic material, such as paint chips, pebbles, and other debris is not attracted to the rotating metallic drum and, thus, drops before entering the airwash module, as shown. Airflow tube(s) extend past a drop zone of the paint chips and other debris, as shown. The airflow tube(s) may have air drawn through the tube(s) by a vacuum (not shown), as understood in the art, so as to cause airflow that serves as an airwash in the blast media airwash module. Rather than using a vacuum, a blower (not shown) may be used to push the air so as to create the airflow, as understood in the art.

As shown, the blast media drops from the rotating magnetic drum into the blast media airwash module. Within the blast media airwash module is a removable airwash cartirdge, in accordance with the principles of the present invention. The removable airwash cartridge includes a successive number of angular feedplates with lips extending horizontally therefrom. The angular feedplates may have angles that provide for a certain flow rate. In one embodiment, the angles are approximately 41 degrees. Alternative angles that adjust flow rate based on different blast media material, size of blast media, desired operation speed, and so forth may be utilized in accordance with the principles of the present invention. The blast media flows down each of the angular feedplates and off the lips so that the flow of the blast media between the lips and angular feedplates are airwashed by the airflow. Prior to a lip, a metering gate or edge (not shown) may be used to control the flow of blast media onto the airwash lip. The use of the metering gate tends to even the flow of grit crossing the lip, thus allowing for a more even and controlled cleaning process. The length of the lip can vary from a matter of inches to tens of feet depending on the size and capacity of the airwash. For the removable airwash cartridge, the overall size is limited so as to be limited in weight. As an example, the dimensions may be 10″×10″×24″.

Multiple Airwash Process Using Multiple Lips

The exact configuration of the lips or lips can vary depending upon the characteristics of the material being cleaned. Airwashes can include a single lip dropping to a single landing zone or can include multiple lips, creating multiple airwashes as the grit falls by gravity through the airwash component.

Angle of Repose

To vary the speed of the grit prior to hitting the lip, the angular feedplate leading to the lip can vary, typically in relation to the angle of repose of the media or material being cleaned. The angle of repose is the angle at which a material flows on itself For instance, common sand typically is assumed to have an angle of repose of about 30 degrees. Steel grit tends to have an angle of repose of about 41 degrees.

Because materials typically flow smoother when flowing across themselves, it is common to allow some material to build up leading back from the lip to insure that the grit or material is always flowing over itself, not the bare surface behind the lip. The angle of the angular feedplates is typically below the angle of repose of the material being used (e.g., 38-40 degrees for steel grit).

Variability of Elements in a System

Many elements can be varied, including the length of the airwash, angle, depth of buildup prior to the lip, length of lip and other aspects. The elements may be varied because of the characteristics of the dry media or material being cleaned or because of the anticipated range of moisture that could exist during operation of the airwash. The opening between the lip or lips and the landing zone can also be changed to change the velocity of air and static pressure of such air as it passes by the falling stream of media. A fan or fans used to propel the air past the media or material can also be varied to a high degree, changing the speed of the air past the media. Thus, there area many elements that can be changed to deliver different results during the airwash cleaning process.

Removable Airwash

On systems that could be stationary or mobile (as on a trailer that is moved to different sites), it may be beneficial to have different configurations of this airwash for different conditions involving moisture, media size, media shape, media density, etc. The different configurations may be used for the purposes of testing various options to get the best results or specifically matching a configuration to a specific media or material. A removable airwash also allows for inspection or cleaning by the operator. In one embodiment, the airwash may have a clear end surface that provides for a user to view flow of the blast media within the airwash.

Cassette or Cartridge Format

Because the airwash cartridge may need to be removed from time to time at different intervals, it is appropriate to design the airwash such that this can be done quickly and easily by the operator of the system. Typically, the cassette or airwash cartridge may be removed by one of two ways, either by pulling/pushing in line with the airwash lip or perpendicular to it. If removed in-line with the airwash lip, such a configuration facilitates seeing the entire length of the lip that leads to the airwash stages. If removed perpendicular to the lip, it allows easy viewing facing the entire lip head on.

Because the airflow is typically horizontal across the airwash lip, the removal in-line with the lip allows other options, such as a viewing pane or removable inspection panel. Having the lit in-line allows an operator to watch the actual airwash separation process while the machine is operating, which is valuable for a number of reasons.

Removable and Adjustable Cassette or Cartridge

Adjustability of elements may be integrated into the removable airwash cartridge to allow adjustment of the separation in addition to allowing removal of the cassette or cartridge. For example, adjustability of angle of the angular feedplates, length of lips, width of slats in walls for the airflow, and so forth may be provided, thereby allowing an operator to adjust mechanical parameters to change operation of the airwash. Adjustability may further allow for the basic abrasive blasting machine with in-feed and out-flow paths to stay unchanged, and allow the more complex airwash separation process to be modified by replacing the cassette or cartridge and/or be adjusted within the cassette or cartridge. In one embodiment, the adjustability is manual. Alternatively, the adjustability is semi-automatic or automatic, thereby providing operators with even more options.

To secure the cassette or cartridge in the unit, numerous locking devices can be used including but not limited to bolts, bolted clamps, lever clamps, etc. To keep water from entering the units, a water shield, seal or gasket may be used To ensure that the cartridge is correctly inserted into the machine, an alignment “key” may be configured on the machine with a matching alignment “key” on the cartridge.

FIG. 2 is an illustration of a zoomed-in view of the blast media airwash module of the abrasive blasting system of FIG. 1. As shown, the blast media drops and flows down the angular feedplate, collects on the lip, and drops to the next angular feedplate. During the drops, airflow passes across the blast media, thereby removing dust and light-weight blast media that is no longer useful as blast media. The dust and light-weight blast media is pushed through airflow vents and upward to another airflow vent (see FIG. 1).

FIG. 3 is an illustration of an illustrative removable airwash cartridge of an abrasive blasting system. The airwash cartridge is shownt to be pulled out partially to show ease of removal. As shown, the removable airwash cartridge has the angular feedplates and lips in-line with the cartridge. If the end-plate attached to the handle had a window or was clear (e.g., Plexiglas), then an operator could view the operation of the airwash module. It should be understood that any other configuration of removable airwash cartridge, including rollers, such as on a drawer, that provides for easier removal may be utilized. Alternative configurations that provide for the same or similar functionality may be utilized in accordance with the principles of the present invention.

FIG. 4 is an illustration of the removable airwash cartridge of the abrasive blasting system of FIG. 3. The airwash cartridge is shown on its end for illustration purposes.

The previous description is of a preferred embodiment for implementing the invention, and the scope of the invention should not necessarily be limited by this description. The scope of the present invention is instead defined by the following claims. 

1. An abrasive blasting system, comprising: a magnetic drum; an airflow generator configured to create airflow; a removable airwash cartridge that includes one or more angular feedplates with lips extending therefrom.
 2. The abrasive blasting system according to claim 1, wherein the angular feedplates are angled at approximately 41 degrees.
 3. The abrasive blasting system according to claim 1, wherein the angular feedplates are adjustable in angle.
 4. The abrasive blasting system according to claim 1, wherein a sidewall of the removable airwash cartridge has at least a portion that is clear to enable a user to view into the removable airwash cartridge.
 5. A method of manufacturing an abrasive blasting system, said method comprising: configuring a blast media airwash module; and inserting a removable airwash cartridge within the blast media airwash module.
 6. The method according to claim 5, further comprising adjusting at least one element in the removable airwash cartridge. 